New York: An unidentified gunman opened indiscriminate fire outside the iconic Empire State Building here on Friday killing at least one person and injuring 10 others, before being shot down by the police, the third such incident in the US in nearly one month.

"The shooter, who was one of the two killed, was shot dead by police," a New York Police Department spokesperson said.

Witnesses said the gunman was wielding a large gun and was shot at least three times. "Ten people were injured in the shooting incident," the spokesperson said. Official sources said FBI is also investigating the incident and it is on the scene of the shooting.

As per preliminary inputs, shooting was apparently sparked by a dispute between co-workers at a business located inside the Empire State Building, also a popular tourist destination.

Two law enforcement officials said investigators have concluded that the shooting had no connection to terrorism and that it appeared to stem from a domestic dispute of some kind, and a third said it may have been sparked by a robbery or dispute in the street, a newspaper said in a report.

Construction worker Chris Ogden was working on a scaffold above the building's 33rd Street entrance when he watched in disbelief as the gunman — in a suit and carrying a briefcase — opened fire, the daily said.

"He shot the guy in the head," said Ogden, 23. "The guy went down. He took a second shot when he was down". The well-dressed shooter then "walked down the block, like nothing was happening, real casual," Ogden said. "We were screaming from the top, 'It's the guy in the grey suit!'" the report quoted him.

The Empire State Building is one of the most famous skyscrapers in the world, and one of New York City's best-known tourist attractions. This is the third shootout in US in nearly one month and the second in August.

On August 5, a white supremacist had opened fire in a Gurdwara in Wisconsin killing six Sikh worshippers. On July 20, a gunman had opened fire in a Colorado theatre killing 12 and injuring 57.